In general, an electromagnetic induction type power supply device that is based on a current transformer is installed on a power link in which a large amount of current flows, such as a power line, a bare conductor line or a busbar, to induce a current from the power link, generate power by using the induced current and supply actuating power to equipment needing power (hereinafter, referred to as “power-needing equipment”).
A typical current induction type power supply device includes a current transformer that induces an alternating current (AC) current from the power link, and a rectifier that converts the AC current induced from the current transformer into direct current (DC) power and transmits the DC power to a device needing power (hereinafter, referred to as “power-needing device”).
However, such a typical power supply device has the following limitations.
(1) Since a current flowing in the power link is interrupted when the power link is out of order, is replaced or repaired, an induced current is not generated and thus there is a limitation in that it is difficult to supply power.
(2) When a typical cylindrical current transformer is used, there is a limitation in that there is a need for the current transformer to be installed or separated when the power link is initially installed or artificially after power supply to the power link is cut off.
(3) When the load of the power-needing device changes, there is a limitation in that there is a need for a new power supply device to be designed and manufactured because it is difficult to increase and decrease the output of a power supply device as necessary.
(4) Since power generated in the process of inducing over-current by the current transformer is transmitted to the power-needing device as it is or is not used up by the power supply device for a necessary time, there is a limitation that adversely affects the lifespan of power-needing equipment or the lifespan of the power supply device.
(5) Even if over-current is not generated by the current transformer, there is a limitation that adversely affects the power supply device and the power-needing equipment by generating and supplying unnecessary power because there is no need to supply power exceeding power needed by the power-needing device.
(6) Even when the size of a current flowing in a general power link decreases to 15 A, it is possible to configure a system that may supply power to a minimum of a power-needing device only when each current transformer has to generate at least 1.2 W or more power, but since most typical current transformer based power supply devices need a minimum power link current of 30 A or more, depends on a switch operation according to the size of a line current or has an auxiliary battery for the operating source of an internal power supply device, there is a limitation in application places that do not correspond to the needs of the minimum current of the general power link.
(7) In a structure that includes a plurality of current transformers, the outputs of the current transformers are connected in parallel to be connected directly to a single power supply module unit to increase an output, but when the current transformers do not have the same characteristics, the output summed by interaction does not linearly increase and thus there is a limitation in that the uniformity of the output quality of a power supply device decreases.
(8) Since a typical electromagnetic induction type power supply device is designed and manufactured in such a manner that a current transformer and a power converting unit independently operate, there are limitations in that it is difficult to perform module-dependent management according to individual performance and output and even the same system experiences a significant variation in performance according to installation methods and orders.